KR20230074306A - Method for producing yttrium oxide-containing thin film by atomic layer deposition - Google Patents

Abstract

A step of introducing a raw material gas containing tris(b-butylcyclopentadienyl)yttrium into a treatment atmosphere to deposit tris(b-butylcyclopentadienyl)yttrium on the gas, and a reactive gas containing water vapor A method for producing a thin film containing yttrium oxide by an atomic layer deposition method, including a step of oxidizing yttrium by introducing it into a treatment atmosphere and reacting with tris(tertiary butylcyclopentadienyl)yttrium deposited on the substrate.

Description

Manufacturing method of yttrium oxide-containing thin film by atomic layer deposition {METHOD FOR PRODUCING YTTRIUM OXIDE-CONTAINING THIN FILM BY ATOMIC LAYER DEPOSITION}

The present invention relates to a method for producing a thin film containing yttrium oxide by an atomic layer deposition method.

It is known that the yttrium oxide thin film has high heat resistance, plasma resistance, and light transmittance, and can be used for a heat-resistant protective film, a plasma-resistant protective film, and an optical thin film.

Examples of the thin film production method include a sputtering method, an ion plating method, an MOD method such as a coating pyrolysis method and a sol-gel method, a CVD method, and an atomic layer deposition method (hereinafter sometimes referred to as an ALD method). Since the quality is good, the CVD method or the ALD method is mainly used.

Patent Document 1 discloses a method for producing a yttrium oxide thin film by a CVD method using tris(tertiary butylcyclopentadienyl)yttrium as a raw material and using nitrogen gas and oxygen gas.

Further, Patent Literature 2 describes that tris(tertiary butylcyclopentadienyl)yttrium can be used in a CVD method or an ALD method. Also, in the same document, when tris(tertiary butylcyclopentadienyl)yttrium is used in the CVD method, oxygen, ozone, nitrogen dioxide, nitrogen monoxide, water vapor, hydrogen peroxide, hydrogen, mono and organic amine compounds such as alkylamines, dialkylamines, trialkylamines, and alkylenediamines, hydrazine, and ammonia. As in the method disclosed in this document, when a thin film containing yttrium oxide is produced by a CVD method using tris(tertiary butylcyclopentadienyl)yttrium, a reaction temperature of 250°C to 800°C is required. In particular, in the case of producing a high-quality yttrium oxide-containing thin film by the CVD method as described in Examples, a reaction temperature of around 450°C was required.

Japanese Unexamined Patent Publication No. 2008-274374 Japanese Unexamined Patent Publication No. 2005-068074

In the case of manufacturing a yttrium oxide-containing thin film by a CVD method in a conventionally known method, a large amount of energy is required to vaporize a raw material serving as a source of yttrium atoms. In addition, since the reactivity of the raw material serving as a source of yttrium atoms and the reactive gas is low, a reaction temperature of around 450° C. is required, making it difficult to manufacture a high-quality yttrium oxide-containing thin film at a low reaction temperature.

As a result of repeated studies, the present inventors have found that a method for producing a yttrium oxide-containing thin film by an atomic layer deposition method having a specific process can solve the above problems, and reached the present invention.

The present invention provides (A) a step of introducing a source gas containing tris(tertiary butylcyclopentadienyl)yttrium into a treatment atmosphere to deposit tris(tertiary butylcyclopentadienyl)yttrium on the gas (hereinafter , (sometimes abbreviated as step (A)) and (B) introducing a reactive gas containing water vapor into the treatment atmosphere and reacting with tris(tertiary butylcyclopentadienyl)yttrium deposited on the gas. To provide a method for producing a thin film containing yttrium oxide by an atomic layer deposition method, including a step of oxidizing yttrium (hereinafter sometimes abbreviated as step (B)).

According to the present invention, a smooth yttrium oxide-containing thin film of good quality with low residual carbon can be manufactured with high productivity at a low reaction temperature.

1 is a flowchart showing an example of a method for producing a yttrium oxide-containing thin film according to the present invention.
Fig. 2 is a schematic view showing an example of an ALD method apparatus used in the method for producing a yttrium oxide-containing thin film according to the present invention.
Fig. 3 is a schematic diagram showing another example of an ALD method apparatus used in the method for producing a yttrium oxide-containing thin film according to the present invention.
Fig. 4 is a schematic diagram showing another example of an ALD method apparatus used in the method for producing a yttrium oxide-containing thin film according to the present invention.
Fig. 5 is a schematic view showing another example of an ALD method apparatus used in the method for producing a yttrium oxide-containing thin film according to the present invention.

The method for producing a yttrium oxide-containing thin film by the atomic layer deposition method of the present invention can use the same procedure as the well-known general atomic layer deposition method, but it is essential to combine the steps (A) and (B) described later That is a feature of the present invention.

Step (A) in the production method of the present invention introduces a raw material gas containing tris(tertiary butylcyclopentadienyl)yttrium into a treatment atmosphere, and in the gas phase, tris(tertiary butylcyclopentadienyl) This is the process of depositing yttrium. Here, "deposit" refers to a concept including adsorption of tris(tertiary butylcyclopentadienyl)yttrium on a substrate. In step (A), by using a source gas containing tris(tertiary butylcyclopentadienyl)yttrium and combining this with step (B), a high-quality yttrium oxide-containing thin film can be produced at a low reaction temperature. There is an effect that there is. The raw material gas containing tris(tertiary butylcyclopentadienyl)yttrium in this step preferably contains 90 vol% or more of tris(tertiary butylcyclopentadienyl)yttrium, and preferably 99 vol% or more. more preferable

The method of vaporizing tris(tertiary butylcyclopentadienyl)yttrium in step (A) is not particularly limited, and can be carried out by vaporizing an organometallic compound used in a well-known general atomic layer deposition method. can For example, it can be vaporized by heating or reducing pressure within the raw material container of the ALD method apparatus shown in FIG. 2 . As for the temperature at the time of heating, the range of 20 degreeC - 200 degreeC is preferable. Further, in step (A), the gas temperature at the time of depositing the vaporized tris(tertiary butylcyclopentadienyl)yttrium on the substrate is preferably in the range of 20°C to 300°C, and 150°C to 250°C. more preferable

As the material of the base in the present invention, for example, silicon; Indium arsenic, indium gallium arsenic, silicon oxide, silicon nitride, silicon carbide, aluminum oxide, aluminum nitride, tantalum oxide, tantalum nitride, titanium oxide, titanium nitride, titanium carbide, ruthenium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, gallium nitride ceramics such as; glass ; Metals, such as platinum, ruthenium, aluminum, copper, nickel, cobalt, tungsten, and molybdenum, are mentioned. Examples of the shape of the substrate include a plate shape, a spherical shape, a fiber shape, and a scale shape. The substrate surface may be flat or may have a three-dimensional structure such as a trench structure.

Step (B) in the production method of the present invention introduces a reactive gas containing water vapor into the treatment atmosphere, and reacts with tris(tertiary butylcyclopentadienyl)yttrium deposited on the gas to oxidize yttrium. It is a process of making In step (B), by using a reactive gas containing water vapor, there is an effect that damage to the body or surrounding members can be reduced.

The reactive gas containing water vapor in this step may be a gas composed of water vapor or a mixed gas with gases such as argon, nitrogen, oxygen, and hydrogen. The concentration of water vapor in the case of a mixed gas is preferably within the range of 0.001 vol% to 50 vol%, more preferably 0.01 vol% to 10 vol%, still more preferably 0.01 vol% to 5 vol%.

The method of introducing the reactive gas containing water vapor into the treatment atmosphere in the step (B) is not particularly limited, and can be introduced in the same manner as the method of introducing the reactive gas used in well-known general atomic layer deposition methods. , it is preferable to introduce a previously vaporized reactive gas into the processing atmosphere.

The thin film containing yttrium oxide in the present invention may be a thin film containing 5% by mass or more of yttrium oxide. Examples of compounds contained in the thin film other than yttrium oxide include yttria stabilized zirconia, yttrium orthovanadate, yttrium dioxide sulfate, yttrium barium copper oxide, and yttrium aluminate. Among these, the production method of the present invention is preferable as a method for producing a thin film made of yttrium oxide.

For example, a method for producing a yttrium oxide thin film on a silicon substrate by the production method of the present invention will be described using the flow chart in FIG. 1 . Here, it is assumed that the apparatus for the ALD method shown in FIG. 2 is used.

First, a silicon gas is installed in a film formation chamber. A method for installing the silicon substrate is not particularly limited, and the substrate may be installed in the film formation chamber by a well-known general method. In addition, tris(tertiary butylcyclopentadienyl)yttrium is vaporized in a raw material container, and this is introduced into a film formation chamber at 20°C to 300°C, preferably 150°C to 300°C, more preferably 200°C to 200°C. It is deposited (adsorbed) on a silicon substrate heated to 300°C, particularly preferably from 200°C to 250°C (Step (A)).

Next, tris(secondary butylcyclopentadienyl)yttrium not deposited on the silicon substrate is exhausted from the film formation chamber (exhaust step 1). Ideally, the tris(bbutylcyclopentadienyl)yttrium not deposited on the silicon substrate is completely evacuated from the deposition chamber, but need not be completely evacuated. Examples of the evacuation method include a method of purging the inside of the system with an inert gas such as helium or argon, a method of evacuating the system by reducing the pressure in the system, or a method in which these are combined. 0.01 Pa - 300 Pa are preferable, and, as for the pressure reduction degree at the time of making it pressure-reduced, 0.1 Pa - 100 Pa are more preferable.

Next, a gas containing water vapor is introduced into the film formation chamber as a reactive gas to react with tris(b-butylcyclopentadienyl)yttrium deposited on the silicon substrate to oxidize yttrium (Step (B)). At this time, it is preferable to vaporize water in advance and introduce it in a state of steam. The gas temperature in the case of reacting water vapor with tris(tertiary butylcyclopentadienyl)yttrium in this step is preferably in the range of 20°C to 300°C, preferably 150°C to 300°C, more preferably 200°C to 300°C, particularly preferably 200°C to 250°C. The difference between the gas temperature in the step (A) and the gas temperature in the step (B) is preferably in the range of 0°C to 20°C as an absolute value. It is because the effect that warpage of the yttria-containing thin film does not occur easily is confirmed by adjusting within this range.

Next, unreacted water vapor and by-produced gas are exhausted from the film formation chamber (exhaust process 2). Ideally, unreacted water vapor and by-produced gases are completely exhausted from the reaction chamber, but need not be completely exhausted. Examples of the evacuation method include a method of purging the inside of the system with an inert gas such as helium or argon, a method of evacuating the system by reducing the pressure in the system, or a method in which these are combined. 0.01 Pa - 300 Pa are preferable, and, as for the pressure reduction degree in the case of reducing pressure, 0.1 Pa - 100 Pa are more preferable.

Thin film deposition by a series of operations consisting of the above (A) process, evacuation process 1, (B) process and evacuation process 2 is regarded as one cycle, and a plurality of film formation cycles are performed until a yttrium oxide-containing thin film having a required film thickness is obtained. may be repeated several times.

Further, energy such as plasma, light, or voltage may be applied to the manufacturing method of the present invention. The timing for applying these energies is not particularly limited. For example, at the time of introduction of tris(tertiary butylcyclopentadienyl)yttrium gas in step (A), at the time of heating in step (B), It may be the time of evacuation in the system in the evacuation process, or it may be between the said each process.

In the manufacturing method of the present invention, after thin film deposition, an annealing treatment may be performed in an inert gas atmosphere or a reducing gas atmosphere in order to obtain a better film quality, or a reflow step may be provided if step filling is required. do. The temperature in this case is 400°C to 1200°C, preferably 500°C to 800°C.

As the apparatus used for producing the yttrium oxide-containing thin film according to the present invention, a well-known ALD method apparatus can be used. Specific examples of the device include a device capable of bubblingly supplying raw materials for atomic layer deposition as shown in FIG. 2 or a device having a vaporization chamber as shown in FIG. 3 . In addition, as shown in FIGS. 4 and 5, an apparatus capable of performing a plasma treatment on a reactive gas is exemplified. It is not limited to the single wafer type apparatus as shown in Figs. 2 to 5, and an apparatus capable of simultaneously processing a plurality of sheets using a batch furnace can also be used.

Example

Hereinafter, the present invention will be described in more detail with Examples and Comparative Examples. However, the present invention is not at all limited by the following examples and the like.

[Example 1] Preparation of yttrium oxide thin film

By using tris(tertiary butylcyclopentadienyl)yttrium as a raw material for the atomic layer deposition method and producing a yttrium oxide thin film on a silicon wafer 20 times by an ALD method under the following conditions using the apparatus shown in FIG. , 20 thin films were prepared.

For the thin films produced, the composition of each thin film was confirmed by X-ray photoelectron spectroscopy, and all of the obtained thin films were yttrium oxide, and the carbon content was less than the lower detection limit of 0.1 atom%. In addition, when the film thickness was measured by the X-ray reflectance method and the average value was calculated, the film thickness was 7.0 nm on average, and the film thickness obtained per cycle was 0.14 nm on average. As a result of cross-sectional observation using an FE-SEM (a field emission scanning electron microscope manufactured by Hitachi High-Technologies Corporation), the surface of the thin film was smooth.

(condition)

Reaction temperature (silicon wafer temperature): 200 ℃

Reactive Gas:

Argon gas: water vapor = 99.9: 0.1 to 95.0: 5.0 (volume ratio)

A series of steps consisting of the following (1) to (4) was set as one cycle and repeated 50 cycles.

(1) The raw material for the atomic layer deposition method vaporized under conditions of a raw material container temperature: 150° C. and a pressure inside the raw material container: 100 Pa is introduced into a film formation chamber and deposited at a system pressure of 100 Pa for 30 seconds.

(2) Undeposited material is removed by an argon purge for 15 seconds.

(3) A reactive gas is introduced into the film formation chamber and reacted at a system pressure of 100 Pa for 0.2 second.

(4) Unreacted reactive gas and by-product gas are removed by argon purge for 60 seconds.

[Example 2] Preparation of yttrium oxide thin film

Twenty smooth thin films were produced in the same manner as in Example 1, except that the reaction temperature (silicon wafer temperature) was changed to 250°C. When the composition of each thin film was confirmed by X-ray photoelectron spectroscopy, all of the obtained thin films were yttrium oxide, and the carbon content was less than the detection lower limit of 0.1 atom%. In addition, when the film thickness was measured by the X-ray reflectance method and the average value was calculated, the film thickness was 6.5 nm on average, and the film thickness obtained per cycle was 0.13 nm on average. As a result of cross-sectional observation using FE-SEM, the surface of the thin film was smooth.

[Comparative Example 1] Preparation of yttrium oxide thin film

Twenty thin films were fabricated in the same manner as in Example 1, except that the raw material for atomic layer deposition was changed to tris(cyclopentadienyl)yttrium. As a result, although a thin film was formed on the silicon wafer in the first to eighth sheets, the irregularity of the surface of the thin film was large, and a flat thin film could not be formed. In the 9th to 20th sheets, no thin film was formed on the silicon wafer.

[Comparative Example 2] Preparation of yttrium oxide thin film

Twenty thin films were manufactured in the same manner as in Example 1, except that the raw material for atomic layer deposition was changed to tris(2,2,6,6-tetramethyl-3,5-heptanedionate)yttrium. . As a result, although thin films were formed on the silicon wafers in the first to eighth sheets, the irregularities on the surface of the thin films were large, and a flat thin film could not be formed. In the 9th to 20th sheets, no thin film was formed on the silicon wafer.

From the above results, in Examples 1 and 2, smooth yttrium oxide thin films with high productivity and low residual carbon were obtained, but in Comparative Examples 1 and 2, thin films with large surface irregularities were obtained. It was also found that the methods for producing the yttrium oxide thin films of Comparative Examples 1 and 2 had very poor productivity.

Claims (1)

All inventions described herein.

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